This invention relates to the transmission of data between a remote monitoring unit and a central unit, and more particularly to the optimization of such data transfer.
Advances in sensor technology, electronics, and communications have made it possible for physiological characteristics of patients to be monitored even when the patients are ambulatory and not in continuous, direct contact with a hospital monitoring system. For example, U.S. Pat. No. 5,959,529 describes a monitoring system in which the patient carries a remote monitoring unit with associated physiological sensors. The remote monitoring unit conducts a continuous monitoring of one or more physiological characteristics of the patient according to the medical problem of the patient, an example being the heartbeat and its waveform.
Under prescribed conditions, the remote monitoring unit contacts a central unit to communicate information on the condition of the patient. For example, if the remote monitoring unit determines that the monitored physiological data suggests that the patient may be in distress or in an emergency, it may immediately and automatically transfer the monitored data to the central unit over a cellular telephone or comparable communications device. The central unit automatically, or in conjunction with medical personnel who are stationed at or are in contact with the central unit, analyzes the data and coordinates the provision of assistance to the patient when necessary. Where the analysis of the transmitted data indicates that there is no patient situation requiring immediate attention, the data is stored and may also be forwarded to the patient""s physician so that treatments may be altered.
While operable, this approach may in some cases be wasteful of the battery power of the remote monitoring unit and require the expenditure of too much data transfer time over the cellular telephone system with its associated charges. The time of the medical personnel may also be used inefficiently.
There is a need for an improved approach for the control of data transfers between the remote monitoring unit and the central unit. The present invention fulfills this need, and further provides related advantages.
The present invention provides an approach for monitoring a patient and providing support to the patient. The present approach adopts a new data transfer architecture with improved selectivity of data transmission but retention of the data accumulation capability to build the patient history and also the emergency capability to assist the patient on an urgent basis when needed. The battery power of the remote monitoring unit is thereby used more judiciously, the cellular telephone connect time is reduced, and medical personnel time is better managed.
In accordance with the invention, a method of monitoring a patient comprises providing a monitoring apparatus including a remote monitoring unit associated with the patient. The remote monitoring unit includes a sensor that measures a physiological characteristic of the patient such as a cardiogram, a central unit, and a communications device which selectively establishes a communications link between the remote monitoring unit and the central unit. The remote monitoring unit obtains a monitored data set for the patient, analyzes the monitored data set to obtain a derived data set from the monitored data set, and determines from the derived data set that communication with the central unit is required. A communications link is established with the central unit, and the remote monitoring unit transmits to the central unit an initially transmitted data set related to the monitored data set. The central unit analyzes the initially transmitted data set and instructs the remote monitoring unit as to any additional transmitted data set, which may be related to the monitored data set, that is to be transmitted from the remote monitoring unit to the central unit and a time at which the additional transmitted data set is to be transmitted.
The present invention is therefore based in an architecture where the main body of data is not automatically transmitted from the remote monitoring unit to the central unit. That approach is likely to produce unnecessarily large and unnecessarily frequent data transfers which result in depletion of the batteries of the remote monitoring unit and large transmission-time costs. Instead, the central unit analyzes the initially transmitted data set, which is usually a reduced data set that is derived from or determined by the monitored data set, to determine whether a more complete data transfer in the form of the additional transmitted data set is required. If so, that transmission is made at a time specified by the central unit. The time of transmission may be immediate, as when an emergency condition is sensed, or deferred, as when the additional transmitted data set is needed for the patient history. The efficiency of communication is thereby optimized while at the same time meeting the medical requirements for the patient.
The step of the remote monitoring unit analyzing the monitored data set may be accomplished by comparing at least one element of the derived data set to a warning limit. The analysis of the initially transmitted data set may include obtaining a patient history from a memory, and analyzing the initially transmitted data set in relation to the patient history. The central unit may instruct the remote monitoring unit to transmit the additional transmitted data set substantially immediately or at a delayed time. The additional transmitted data set and the monitored data set may be the same or may not be the same data sets.
In one embodiment, the communications device comprises a radio frequency telephone terminal (such as a cellular or satellite telephone terminal) and a land-line telephone terminal. The radio frequency telephone connection may be made at any time, but the land-line telephone terminal is available only when the remote monitoring unit is physically connected to a land line. The transmission of the initially transmitted data set, which usually is a much smaller amount of data than the monitored data set, may be made over the radio frequency telephone connection. Upon analysis at the central unit, if there appears to be the possibility of an emergency wherein more data is needed immediately, the larger additional transmitted data set may be immediately transmitted over the radio frequency telephone connection. On the other hand, where the central unit determines that there is not an emergency but that it would be useful to have the additional transmitted data set for future reference as a part of the patient history, the central monitoring unit may instruct the remote monitoring unit to store and then transmit the additional transmitted data set at a later time over the land-line telephone terminal when such a connection is available or the radio frequency telephone connection when transmission costs are lower (i.e., off-peak hours).
This selective transmission approach, wherein data transmission from the remote monitoring unit is not automatic but instead is under control of the central unit, reduces the amount of data that must be transmitted over a cellular telephone connection or similar expensive communication device. This selectivity reduces cellular telephone connect time and charges to the user, and also may significantly increase the lifetime of the remote monitoring unit between battery charging, because establishing and maintaining the cell phone connection constitutes a significant portion of the battery usage of the remote monitoring unit. The human resources of the medical personnel at or in communication with the central unit are also better utilized. Only those situations that are more likely to be actual emergencies are brought to the attention of those medical personnel, so that they have more time for such potential actual emergencies.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.